.TH LC_REGISTER_VAR 3 "25 Oct 04" "@PACKAGE_STRING@"
.SH NAME
lc_register_var \- Register a variable for automatic processing.

.SH SYNOPSIS
.B #include <libconfig.h>
.sp
.BI "int lc_register_var(const char *" var ", lc_var_type_t " type ", void *" data ", char " opt ");"

.SH DESCRIPTION
The
.BR lc_register_var (3)
function registers a variable for automatic processing.
The
.IR var
parameter specifies the variable name for processing.  This name can exist in a configuration file, an environment variable, or on the command line.
The
.IR opt
parameter specifies the single letter short option that can be specified on the command line to change the value of the variable specified by the
.IR data
parameter.  A value of '\0' can be specified for no short option.

The
.IR type 
parameter is of type
.IR lc_var_type_t
which specifies the type of the
.IR data
parameter.
Valid values for
.IR type
are:
.TP
LC_VAR_STRING
For a string type variable.  The data passed should be of type "char **".  The data will be set to a region of memory that has been allocated with malloc() and can be released be free()'d.
.TP
LC_VAR_LONG_LONG
For a "long long" integer type variable.  The data passed should be of type "long long *".
.TP
LC_VAR_LONG
For a "long" integer type variable.  The data passed should be of type "long *".
.TP
LC_VAR_INT
For a "int" integer type variable.  The data passed should be of type "int *".
.TP
LC_VAR_SHORT
For a "short" integer type variable.  The data passed should be of type "short *".
.TP
LC_VAR_BOOL
For a boolean type variable.  The data passed should be of type "int *".  When a true value is specified the variable is set to 1.  When a false value is specified the variable is set to 0.  Any other value sets the variable to -1.  Valid true values are: enable, true, yes, on, y, and 1.  Valid false values are: disable, false, off, no, n, and 0.
.TP
LC_VAR_FILENAME
Not implemented.
.TP
LC_VAR_DIRECTORY
Not implemented.
.TP
LC_VAR_SIZE_LONG_LONG
For a "long long" integer type that can have size modifiers, such as 'G' or gigabytes, 'M' for megabytes, 'K' for kilobytes.  The data passed should be of type "long long *".
.TP
LC_VAR_SIZE_LONG
For a "long" integer type that can have size modifiers, such as 'G' or gigabytes, 'M' for megabytes, 'K' for kilobytes.  The data passed should be of type "long *".
.TP
LC_VAR_SIZE_INT
For a "int" integer type that can have size modifiers, such as 'G' or gigabytes, 'M' for megabytes, 'K' for kilobytes.  The data passed should be of type "int *".
.TP
LC_VAR_SIZE_SHORT
For a "short" integer type that can have size modifiers, such as 'G' or gigabytes, 'M' for megabytes, 'K' for kilobytes.  The data passed should be of type "short *".
.TP
LC_VAR_SIZE_SIZE_T
For a "size_t" data type that can have size modifiers, such as 'G' or gigabytes, 'M' for megabytes, 'K' for kilobytes.  The data passed should be of type "size_t *".
.TP
LC_VAR_TIME
Not implemented.
.TP
LC_VAR_DATE
Not implemented.
.TP
LC_VAR_BOOL_BY_EXISTANCE
This type of variable takes no arguments, it is set to true (1) by its existance in a configuration file, environment variable, or on the command line.  If it is not specified, the value of the data passed is not changed.  The data passed should be of type "int *".
.TP
LC_VAR_CIDR
This type of variable accepts a CIDR format netmask and IP.  This is not yet implemented. (XXX)
.TP
LC_VAR_IP
This type of variable accepts an IP address in decimal-dot format.  The value is stored in a uint32_t.
.TP
LC_VAR_ADDR
This type of variable accepts an address in either host or decimal-dot format.  The value is stored in a uint32_t.  This is not yet implemented. (XXX)

.SH "RETURN VALUE"
On success 0 is returned, otherwise -1 is returned.

.SH EXAMPLE
.nf
#include <libconfig.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char **argv) {
	int lc_p_ret, lc_rv_ret;
	char *filename = NULL;
	long int counter = -1;

	lc_rv_ret = lc_register_var("Begin", LC_VAR_LONG,
	                            &counter, 'c');
	if (lc_rv_ret != 0) {
		fprintf(stderr, "Error registering variable: %i.\\n",
		        lc_geterrno());
		return(EXIT_FAILURE);
	}

	lc_rv_ret = lc_register_var("File", LC_VAR_STRING,
	                            &filename, 'f');
	if (lc_rv_ret != 0) {
		fprintf(stderr, "Error registering variable: %i.\\n",
		        lc_geterrno());
		return(EXIT_FAILURE);
	}

	lc_p_ret = lc_process(argc, argv, "example", LC_CONF_APACHE,
	                      NULL);

	lc_cleanup();

	if (lc_p_ret != 0) {
		fprintf(stderr, "Error processing configuration: \\
		        %s\\n", lc_geterrstr());
		return(EXIT_FAILURE);
	}

	if (filename != NULL) {
		printf("File specified was: %s\\n", filename);
	} else {
		printf("No filename specified.\\n");
	}

	if (counter != -1) {
		printf("Counter was specified as: %ld\\n", counter);
	} else {
		printf("Counter was not specified.\\n");
	}

	return(EXIT_SUCCESS);
}
.fi

.SH "SEE ALSO"
.BR lc_register_callback (3),
.BR lc_geterrno (3),
.BR lc_geterrstr (3),
.BR lc_cleanup (3),
.BR lc_process_file (3),
.BR lc_process (3)